A long standing problem known to those skilled in the electronics art involves the mismatch between the thermal properties of materials making up an electronic device and the materials making up the substrate to which the device is mounted. Canestaro et al U.S. Pat. No. 4,728,751 addressed the mismatch problem associated with mounting an electronic device, such as a semiconductor chip made primarily of silicon, directly onto an organic substrates, such as printed circuit boards made primarily of glass cloth impregnated with epoxy resin or other suitable materials. Canestaro et al solved the mismatch problem by processing a selected surface portion of a substrate to form a relatively low adhesive area surrounded by a relatively high adhesive area. A circuit line pattern was deposited on the substrate, including circuit lines having termini with stress relief bends located in the relatively low adhesive area on the surface of the substrate. As such, the terminus of each of the circuit lines floats on the surface of the substrate while the remainder of the circuit line is fixed to the relatively high adhesive area on the surface of the substrate. However, the circuit line including the relief bend are co-planar and parallel to the surface of the substrate. Consequently, the lines with the stress relief bend consume a substantial amount of real estate on the substrate.
Ashby, U.S. Pat. No. 3,519,890 also attempted to solve the thermal mismatch problem by interconnecting a microelectronic circuit containing die with a substrate utilizing a meandering conductive line to relieve the stress on the die and conductive line under thermal conditions and temperature cycling. However, the meandering lines did not have a common geometry and as a result took up a substantial amount of valuable area on the mounting substrate.
The present invention provides alternatives to and advantages over the prior art.